Quality of service. Performance, such as transmission rates and error rates, of a communications channel or system.


Type of PIC that combines the PIC and FPC within a single FPC slot.

qualified next hop

Next hop for a static route that allows a second next hop for the same static route to have different metric and preference properties than the original next hop.

quality of service

See QoS.

querier router

PIM router on a broadcast subnet responsible for generating IGMP query messages for the segment.


First-in, first-out (FIFO) number of packets waiting to be forwarded over a router interface. You can configure the minimum and maximum size of the packet queue, queue admission policies, and other parameters to manage the flow of packets through the router.

queue length

For ATM1 interfaces only, a limit on the number of transmit packets that can be queued. Packets that exceed the limit are dropped. See also EPD.


In routing, the arrangement of packets waiting to be forwarded. Packets are organized into queues according to their priority, time of arrival, or other characteristics, and are processed one at a time. After a packet is sent to the outgoing interface on a router, it is queued for transmission on the physical media. The amount of time a packet is queued on the router is determined by the availability of the outgoing physical media, bandwidth, and the amount of traffic using the interface.